This blog post claims: https://grpugh.wordpress.com/2014/10/29/an-undocumented-change-to-captive-network-assistant-settings-in-os-x-10-10-yosemite/ the new URL is now: `http://captive.apple.com/hotspot-detect.html` instead of `http://www.apple.com/library/test/success.html` Do you support that change? Wont be able to test until Monday unfortunately.